OK so my period is now 13 das late...?

So my period is 13 days late and on day ten I tested and it was negative. Is there a chance I am still pregnant? I have had 2 kids already and personally I don't remember how far along I was when I found out. A week before my expected period I had brown spotting only saw after I whipped. This lasted bailey a day. I thought this could of been implantation bleeding. I just want to know if any of this has happened to anyone and just some advice! Thanks to all!